Sensitivity of ground deformation and gravity anomalies in the detection of complex underground magmatic sources

Underground magmatic activity is often detected by analyzing geophysical signals recorder at the Earth's surface such as seismicity, ground deformation, gravitational and magnetic anomalies. Inversion of these signals can provide information on the source characteristics. On the other hand, forward modeling can aid in prediciting expected signals as a onsequence of specific source, and path, properties.
In this work, we employ  a finite element model of magma dynamics and coupled rock mechanics to retrieve ground deformation and gravitational anomalies expected as a consequence of magma arrival from depth into shallower reservoirs. The sensitivity of ground deformation and gravitational anomalies to different magma dynamics patterns is investigated with a parametric study on the effects of buoyancy and overpressurization within the magmatic system. The resulting space-time distribution of ground displacement and gravity anomaly shows that interpretation of observed patterns is not straightforward as soon as the assumption of simple (pressurized ellipsoid, dike) magmatic source is abandoned.  The results of this study suggest cautious interpretations of observed deformation and gravity patterns, in particular in relation to the complexities introduced by the spectrum of forces driving magmatic movements, and the multifaceted magma dynamics across multiple interconnected reservoirs. Similar care is suggested when inverting monitoring signals, especially when combining multiple signals such as those associated with ground deformation and gravity changes, that albeit originating from the same overall dynamics might reflect, under some circumstances, different processes occurring in separate regions of the magmatic domain.